Chocolate & Walnut Birthday Cake

This week has been so crazy. My brain is literally on fire and I feel like my thoughts are spewed out everywhere. I want it to slow down but it won't. I haven't been sleeping well and I am exhausted. Even after only 4 days of work.
So in between all this craziness I managed to find time to bake a birthday cake. I did not have time to search for a recipe online so I used one from the Easy Baking book. When it just came out from the oven, I thought it had to be the saddest-looking cake ever existed! It did not rise as much as I expected and I probably over-baked it a little, making the surface look dry and rough. For the first time in my life I actually iced it too - otherwise it would have been too unpresentable. I was even worried about how it would taste because I could not cut out a small for tasting. But when everyone ate it at dinner, they all liked it and it was delicious. It was rich in chocolate, packed with nuts and not too sweet. The cake actually had a good height as well. And most importantly the birthday boy loved it so that's all that matters :)

Chocolate & walnut cake

4 eggs
100g brown sugar
75g dark chocolate (70% cocoa), broken into pieces
125g plain flour
1 tbsp cocoa powder
2 tbsp butter, melted
115g walnuts, finely chopped

icing:
50g dark chocolate
80g butter
125 icing sugar
2 tbsp milk

1) Preheat the oven to 160 degrees C. Grease a 18cm deep round cake tin and line with baking paper.2) Place the eggs and caster sugar in a large mixing bowl and whisk with an electric whisk for 10 minutes, or until foamy and a trail is left when the whisk is dragged across the surface. Put the chocolate in a heatproof bowl set over a saucepan of gently simmering water until melted.
3) Sift the flour and cocoa together and fold into the egg and sugar mixture with a spatula. Fold in the melted butter, melted chocolate and walnut pieces. Pour into the prepared tin and bake for 30 minutes, or until springy to the touch.
4) Leave to cool in the tin for 5 minutes, then transfer to a wire rack and leave to cool completely.
5) To make the icing, melt the chocolate as above and leave to cool slightly. Beat together the butter, icing sugar and milk until the mixture is pale and fluffy. Whisk in the melted chocolate.
6) Spread the icing over the top of the cake.